Background: Chronic pain affects 40-70% of veterans and is a leading cause of disability, resulting in substantial negative impact on millions of Veterans' lives. Pain reduces quality of lie and is associated with emotional distress when it interferes with work, social and recreational activities, and family life. Pain self-management, which involves treatment adherence, behavioral change, and coping skills, is an effective, evidence-based treatment for chronic pain that has been advocated by both the Institute of Medicine and the 2009 VHA Pain Directive. However, implementation of a pain self-management model in VA is challenging because of limited time and resources in primary care, where most chronic pain is managed. As a result, pharmacological treatments, including opioid analgesics, are frequently the first line of treatment, and pain self-management is under-utilized. Objectives: Evaluation of a Peer Coach-Led Intervention for the Improvement of Pain Symptoms (ECLIPSE) is a randomized controlled trial designed to test the effectiveness of peer coach-delivered pain self-management intervention versus controls receiving a 2-hour class on pain and pain self-management. The primary study outcome is overall pain (intensity and interference), measured by the Brief Pain Inventory (BPI). Methods: ECLIPSE will enroll Veterans from primary care clinics who have chronic musculoskeletal pain. ECLIPSE is a Hybrid Type 1 study designed to test effectiveness, while also examining implementation barriers and facilitators. We will enroll 215 Veteran patients and 40 Veteran peer coaches. The 215 Veterans will be randomly assigned to the peer-coaching arm (n=120) or the control arm (n=95). Peer coaches will be assigned 3 Veterans each. The peer-coaching intervention will last 9 months and coaches and Veterans will be encouraged to meet (in person or by phone) at least bi-weekly. Peer coaches will be provided with a detailed manual and will be trained and supervised by the study nurse, who has delivered pain self- management interventions to Veterans in several previous studies. The primary study outcome is overall pain, measured by the Brief Pain Inventory (BPI) which assesses both pain intensity and interference with activities. Secondary outcomes are self- efficacy, social support, pain coping, patient activation, health-related quality of life, and health care utilization. Outcomes will be assessed at baseline, 6 months (intermediate effect) and 9 months (primary endpoint). We will also conduct interviews with peer coaches, Veteran participants, and VA Patient-Aligned Care Team (PACT) staff to determine facilitators and barriers to implementing a peer coach-led self-management program in primary care in the VA. Innovation: To maximize implementation potential of pain self-management in VA, alternative delivery methods are needed to provide Veterans with education and support needed to self- manage their pain, without requiring additional resources from healthcare teams. A novel and promising approach is a peer coaching model, in which Veterans with chronic pain who are successfully managing their pain offer information, support, and mentorship to other Veterans with pain. Peer support models have been found to be effective in the management of a variety of chronic conditions in VA and non-VA settings.